Alcohol abuse and alcohol dependence have become increasingly serious public health problems in the world today. There is an increasing trend of alcoholic liver injury in China, so alcohol has become the second pathogenic cause of liver injury following viral infection. Alcohol-induced liver injury mainly includes alcoholic fatty liver, alcoholic hepatitis, alcoholic liver fibrosis and alcoholic cirrhosis. Alcoholic liver injury can also lead to other diseases and conditions such as the problem that blood cannot be filtered thoroughly by liver, hyperlipidemia, cardiovascular and cerebrovascular diseases, lower liver catabolism, diabetes, gallstones, kidney disease, acute fatty liver of pregnancy and damage to the digestive system. Therefore, it is important to investigate the pathogenesis of alcoholic liver diseases and seek for prevention and therapy measures against alcoholic liver injury.
It is believed that the alcoholic liver injury mainly results from toxic metabolites of ethanol metabolism in the liver cells and the subsequent metabolic disorders. The specific reasons of alcoholic liver injury include: 1. toxic effects of acetaldehyde: acetaldehyde interacts with cysteine, glutathione and vitamin E to promote lipid peroxidation; acetaldehyde combines with multiple proteins of liver as antigens to stimulate the body to produce antibodies, causing corresponding immune response and resulting in the damage to liver cells; and acetaldehyde can also combine with important functional groups of enzymes, resulting in the changes of enzyme activities, thereby affecting the enzyme function. 2. Adverse effects of free radicals: A large amount of free radicals and reactive oxygen species can be produced during ethanol metabolism; these free radicals not only can damage the liver cells directly, but also increase the susceptibility of liver cells to lipid peroxidation, thus causing liver cell damage. 3. Induction of endotoxin: ethanol intake disturbs intestinal microflora and destroys the integrity of structure and function of the intestinal mucosa at the same time, so as to increase the permeability of intestinal mucosa. Therefore the endotoxin level in blood is increased to produce a plurality of cytokines, among which inflammatory cytokines cause liver cell injury. At present, the main treatments for alcoholic liver injury include abstinence, nutritional therapy, drug therapy, gene therapy, and therapies for alcoholic liver disease-related diseases. The most commonly used method is drug treatment, which has certain effects but many deficiencies. For example, many drugs may promote more blood lipids to be metabolized in the liver, which promotes lipid accumulation in the liver and cause liver function damage. The metabolism of these drugs in liver may possibly increase the liver burden further; some drugs take effect slowly, and even cause drug resistance and side effects. Therefore, researchers are actively developing new treatments and intervention strategies for alcoholic liver diseases. Probiotics without drug resistance and side effects have been widely used to improve human health, especially directed for prevention and treatment of alcoholic liver diseases (FIG. 5), gradually causing public concern.
Probiotics are living microorganisms that have beneficial effects on the host when administered in adequate amounts. The said probiotics include Lactobacillus, Bifidobacterium and some Streptococcus strains. Generally, they have special physiological effects and health functions such as regulating intestinal microflora of the host, treating antibiotic-associated diarrhea, reducing blood cholesterol levels, inhibiting infection resulting from pathogenic bacteria such as Escherichia coli, Helicobacter pylori and so on. In addition, probiotics can effectively eliminate free radicals to promote antioxidative activity of the host, reduce the endotoxin level and regulate the immune system. These functions reveal that probiotics can play a role in relieving alcoholic liver injury. However, it has been rarely reported that probiotics have hepato-protective effects. Therefore, it is significant to investigate the application of probiotics on the uses as health foods to relieve alcoholic liver injury. With increasing attention on alcoholic liver injury and wider uses of probiotics, the dietary intervention of probiotics and probiotic products on alcoholic liver diseases will have a very broad market prospects.
At present, the published patent applications for the prevention and treatment of alcoholic liver injury mainly focuses on Chinese medicine compositions. For example, CN101224232A discloses that flavones extracted from the root of radix puerariae can inhibit the increasing permeability of small intestine, reduce the blood alcohol concentration, decrease the alcohol absorption and relieve alcoholic liver damage. CN 101961367A discloses a Chinese medicine composition for prevention of alcoholic liver injury, composed of fungal polysaccharide and silybum marianum extract with good solubility, rapid disintegration in the gastrointestinal tract to enhance the immunity of the host and to function as an adjuvant to protect the liver from alcoholic injury. CN 102058632A and CN 102160637A also separately disclose the protective effects of herbs and their extracts on alcoholic liver injury. As for dairy products, such as CN 101623032A discloses a kind of milk that can help protect the host from alcoholic liver injury. Such milk added with soluble dietary fiber, lecithin, soybean peptide and so on can enhance liver function, accelerate alcohol metabolism and relieve alcoholic liver injury. CN 101328469A also discloses a Streptococcus thermophilus grx02 that protects the liver from alcoholic injury. However, these patents do not fully relate to a probiotic Lactobacillus that can regulate intestinal flora and relieve chronic alcoholic liver injury.
Therefore, it is necessary to search for probiotics and related foods and compositions that can regulate intestinal microflora and relieve chronic alcoholic liver injury.